During the current period of support we have developed a facility for fabrication and analysis of cDNA microarrays and identified patterns of gene expression in different brain regions from alcoholic and non- alcoholic cases. This success of this work has been facilitated by a strong international collaboration with investigators from the University of Queensland, Australia. Several key findings from these studies suggest that distinct patterns of gene expression in the frontal cortex are altered in alcoholics, and that these alcohol- responsive genes belong to functionally diverse families. These results raise several important questions that will be addressed during the next period of support. These include the following: (1) Can these gene clusters be generalized or refined to identify novel functional pathways in a larger and more diverse sample of cases? (2) Similarly, are there clusters of brain proteins that are changed in alcoholic individuals? (3) Can these genomic and proteomic profiles be used to define functionally related clusters that define disruptions of signaling in frontal cortex that are responsible for at least some aspects of alcoholism. (4) Are there patterns of gene expression in nucleated blood cells that can serve as biomarkers for alcohol consumption, dependence, or abstinence? The Specific Aims are: 1) Test the hypothesis that patterns of brain gene expression can identify novel functional pathways that are altered in alcoholics. It is also proposed that brain gene expression profiles will reflect drinking history, and severity of liver and other organ damage, 2) Global proteomics analysis will identify novel proteins that differ between individual alcoholic and non-alcoholic cases, 3) Test the hypothesis that patterns of gene expression in nucleated blood cells can distinguish between non-alcoholics, actively drinking alcoholics, and abstinent alcoholics. cDNA microarrays will be used to test expression of thousands of genes at a time as an initial screening method to identify potential blood-based biomarkers of alcoholism. These studies will provide new targets for addiction pharmacotherapy as well as new diagnostic tools for alcohol abuse and alcoholism.